/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.metrics;

import org.apache.flink.configuration.Configuration;
import org.apache.flink.configuration.MetricOptions;
import org.apache.flink.metrics.Metric;
import org.apache.flink.metrics.MetricConfig;
import org.apache.flink.metrics.MetricGroup;
import org.apache.flink.metrics.reporter.MetricReporter;
import org.apache.flink.runtime.concurrent.FutureUtils;
import org.apache.flink.runtime.testutils.MiniClusterResource;
import org.apache.flink.runtime.testutils.MiniClusterResourceConfiguration;
import org.apache.flink.util.TestLogger;

import org.junit.ClassRule;
import org.junit.Test;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

import static org.apache.flink.configuration.MetricOptions.REPORTERS_LIST;
import static org.apache.flink.configuration.MetricOptions.SYSTEM_RESOURCE_METRICS;
import static org.junit.Assert.assertEquals;

/**
 * Integration tests for proper initialization of the system resource metrics.
 */
public class SystemResourcesMetricsITCase extends TestLogger {

	@ClassRule
	public static final MiniClusterResource MINI_CLUSTER_RESOURCE = new MiniClusterResource(
		new MiniClusterResourceConfiguration.Builder()
			.setConfiguration(getConfiguration())
			.setNumberTaskManagers(1)
			.setNumberSlotsPerTaskManager(1)
			.build());

	private static Configuration getConfiguration() {
		Configuration configuration = new Configuration();
		configuration.setBoolean(SYSTEM_RESOURCE_METRICS, true);
		configuration.setString(REPORTERS_LIST, "test_reporter");
		configuration.setString(MetricOptions.SCOPE_NAMING_JM, "jobmanager");
		configuration.setString(MetricOptions.SCOPE_NAMING_TM, "taskmanager");
		configuration.setString("metrics.reporter.test_reporter.class", TestReporter.class.getName());
		return configuration;
	}

	@Test
	public void startTaskManagerAndCheckForRegisteredSystemMetrics() throws Exception {
		assertEquals(1, TestReporter.OPENED_REPORTERS.size());
		TestReporter reporter = TestReporter.OPENED_REPORTERS.iterator().next();

		reporter.patternsExhaustedFuture.get(10, TimeUnit.SECONDS);
	}

	private static List<String> getExpectedPatterns() {
		String[] expectedGauges = {
			"System.CPU.Idle",
			"System.CPU.Sys",
			"System.CPU.User",
			"System.CPU.IOWait",
			"System.CPU.Irq",
			"System.CPU.SoftIrq",
			"System.CPU.Nice",
			"System.Memory.Available",
			"System.Memory.Total",
			"System.Swap.Used",
			"System.Swap.Total",
			"System.Network.*ReceiveRate",
			"System.Network.*SendRate"
		};

		String[] expectedHosts = {
			"taskmanager.",
			"jobmanager."
		};

		List<String> patterns = new ArrayList<>();
		for (String expectedHost : expectedHosts) {
			for (String expectedGauge : expectedGauges) {
				patterns.add(expectedHost + expectedGauge);
			}
		}
		return patterns;
	}

	/**
	 * Test metric reporter that exposes registered metrics.
	 */
	public static final class TestReporter implements MetricReporter {
		public static final Set<TestReporter> OPENED_REPORTERS = ConcurrentHashMap.newKeySet();
		private final Map<String, CompletableFuture<Void>> patternFutures = getExpectedPatterns().stream()
			.collect(Collectors.toMap(pattern -> pattern, pattern -> new CompletableFuture<>()));
		private final CompletableFuture<Void> patternsExhaustedFuture = FutureUtils.waitForAll(patternFutures.values());

		@Override
		public void open(MetricConfig config) {
			OPENED_REPORTERS.add(this);
		}

		@Override
		public void close() {
			OPENED_REPORTERS.remove(this);
		}

		@Override
		public void notifyOfAddedMetric(Metric metric, String metricName, MetricGroup group) {
			final String metricIdentifier = group.getMetricIdentifier(metricName, name -> name);
			for (final String expectedPattern : patternFutures.keySet()) {
				if (metricIdentifier.matches(expectedPattern)) {
					patternFutures.get(expectedPattern).complete(null);
				}
			}
		}

		@Override
		public void notifyOfRemovedMetric(Metric metric, String metricName, MetricGroup group) {
		}
	}
}
